1. Technical Field
The present invention relates to liquid containers and liquid-ejecting apparatuses.
2. Related Art
Liquid-ejecting apparatuses eject liquid supplied by liquid containers from ejecting heads to targets that face the ejecting heads. An example of such liquid-ejecting apparatuses includes ink-jet printers.
In some ink-jet printers, cartridges serving as liquid containers are not installed in carriages (so-called off-carriage type). Cartridges of the off-carriage type include ink packs formed of flexible film bags filled with ink and cases that accommodates the ink packs. The ink is supplied from the cartridges to the ejecting heads by differences in potential head with respect to the ejecting heads or by pressure to the ink packs using pressurized air.
Recently, consumption of ink in cartridges per unit time has been increasing due to, for example, increased printing speed of the ink-jet printers. In particular, large-format printers for business use consume great quantities of ink. Under such circumstances, the capacity of cartridges has been increasing.
In relation to this trend, slender cartridges have been proposed. The slender cartridges can have a larger capacity, and can also be installed in known printers. As shown in FIG. 11, a cartridge 100 includes a slender ink pack 101, a case 102 that accommodates the ink pack 101, and a cover 103 that covers the case 102. Moreover, a detecting plate 105 is stuck on the upper surface of the ink pack 101 for detecting a state where the ink level in the ink pack 101 reaches a predetermined value or lower (e.g., out-of-ink state). The detecting plate 105 has substantially the same length as the ink pack 101 in the longitudinal direction thereof, and includes a substantially L-shaped projection 106 at a side end thereof. Moreover, the detecting plate 105 is stuck on the ink pack 101 such that the projection 106 faces a through-hole 107 formed in the case 102.
As the ink inside the ink pack 101 is consumed, the ink pack 101 gradually collapses. With this, the detecting plate 105 moves in a direction along which the detecting plate 105 approaches the bottom surface of the case 102. When the ink is exhausted, the projection 106 of the detecting plate 105 enters the through-hole 107 of the case 102, and the projection 106 comes into contact with a detecting device (not shown) disposed below (in the drawing) the case 102. Thus, the detecting device detects the out-of-ink state of the ink pack 101.
However, when the size of the detecting plate 105 is not appropriately set, the detecting plate 105 may interrupt the flow of the ink inside the ink pack 101, and an out-of-ink state may be detected even when the ink level is higher than a predetermined value. To solve this problem, JP-A-2001-260390 discloses a cartridge for improving accuracy of detection by controlling the size of the detecting plate 105 on the basis of a ratio set according to the lengths of sides of the ink pack 101.
However, the cartridge disclosed in JP-A-2001-260390 is intended for use with detecting plates of known shapes. Therefore, when the above-described detecting plate 105 is adopted to a slender cartridge 100, the detecting plate 105 needs to be slender in accordance with the preset ratio. This can cause the attitude of the detecting plate 105 disposed on the flexible ink pack 101 to be unbalanced and unstable. Thus, a large load can be locally applied to the ink pack 101, and the initial value of water head with respect to the ejecting head can be increased. As a result, a normal ink meniscus cannot be formed at the nozzle of the ejecting head, thereby causing discharge failure. Furthermore, the ink can leak out from the nozzle at a time when the ink is not supposed to be discharged.
Moreover, the ink pack 101 can be easily creased when the detecting plate 105 is stuck on the ink pack 101. The creases formed during sticking of the detecting plate 105 to the ink pack 101 can hinder the transfer of the detecting plate 105, and can cause failure of detection of an out-of-ink state even when the ink level reaches a predetermined value or lower.
In contrast, when the size of the detecting plate 105 is reduced such that the detecting plate 105 is stably positioned on the ink pack 101, the portion on which the detecting plate 105 is stuck is compressed first. Thus, an out-of-ink state can be detected while the ink remains in portions on which the detecting plate 105 is not stuck.